During various connection modes of a wireless communication system, a cell search (CS) process must continuously monitor, (i.e., search for, identify and measure), cells that are part of a list of N cell identities (IDs), (e.g., existing networks employ a list having up to 32 cell IDs). In order to perform cell identification, the CS process attempts to associate primary synchronization code (PSC) correlation peak locations with a particularly listed cell ID, (i.e., one scrambling code per common pilot channel (CPICH)).
In a prior art approach, the CS process takes one PSC correlation peak at a time and use its associated timing information to correlate the received signal with one of the N scrambling codes in an exhaustive manner, (e.g., N=32 scrambling codes). All CPICH correlation values, obtained by accumulating the results of the correlation between the CPICH and the In-phase (I)/Quadrature (Q) baseband received signal, above a certain noise threshold are reported. The procedure exploits the fact that a Primary Synchronization Channel (P-SCH) and the CPICH have timing relationship. In a universal mobile telecommunications system (UMTS) downlink signaling structure, the P-SCH is repeated for the first 10% of each slot. There are 15 slots in each frame of 10 ms duration. The CPICH spans over a 10 ms frame, which is repeated on a per frame basis. The SCAM associates peak locations that are due to P-SCH correlations with respect to fifteen (15) different possible phases of CPICH correlations. These phases correspond to fifteen (15) different slots for a CPICH signal. There is no difference with respect to multipath location estimation by using P-SCH or CPICH. A shortcut is possible by estimating the peak locations in P-SCH processing, and then using SCAM to further associate the detected peaks to CPICH correlation for a particular monitored cell, given the list up to 32 scrambling codes. This process is repeated for each of the PSC correlation peaks calculated during the CS process. The hardware design ensures that there is enough bandwidth in hardware to perform the exhaustive search in the required time.
In order to monitor cells, the current CS approach covers blindly all possible cases. The power consumed by the CS is not negligible especially in IDLE mode. It is desirable to perform the CS and cell identification process with improved efficiency.